The present invention relates to surgical drapes for covering a patient's extremity during an operative procedure.
References known to the applicant and believed to be relevant to the present invention include the following U.S. Pat. Nos. 3,934,582 issued to Gorrie on Jan. 27, 1976; 3,968,792 issued to Small on July 13, 1976; and 3,989,040 issued to Lofgren, et al on Nov. 2, 1976. The Small patent, which is assigned to the assignee of the present invention, teaches various improvements in construction and use of stockinette tubular drapes which are generally made from 100% cotton woven in a seamless tubular structure. This type of tubular knit stockinette is usually woven in a stretch weave which permits the tubular structure to conform very closely to the extremity being draped and to move with the extremity without slipping relatively thereto.
The Gorrie patent discloses a tubular extremity drape having an outer layer of a fluid impervious plastic material which is intended to avoid the one basic problem occurring with the cotton stockinettes. The fabric stockinette absorbs the fluids resulting from surgery, and once it has been wet from inner to outer surface, it no longer provides a sterile barrier. The fluid impervious outer layer will obviously prevent strike-through, that is, the wetting of the drape from the inner to outer surface. But it has been found in practice that in most cases, any material which provides an effective fluid barrier is not as flexible or elastic as the stockinette material. It is highly desirable that once a drape of this type has been placed on a patient's extremity that it remain in its original position and not slide relatively to the extremity. This is due to the fact that, in general, the surgical procedure is performed through an opening, or fenestration, formed in the drape itself. This opening is desirably kept as small as possible and, as a result, any movement of the drape relative to the patient's extremity can interfere with the surgical procedure.
The Lofgren, et al patent discloses one way of insuring that a surgical extremity drape does not move relative to the extremity once it is positioned around The surgical site. The drape provided by Lofgren is similar to that taught by Gorrie in having at least an outer layer of a fluid impervious material. Instead of attempting to make the drape conform closely to the patient's extremity, to prevent slipping, Lofgren provides a pre-formed slit adjacent the open end and an adhesive strip running along both sides and the end of the slit. In this way, the drape may be positioned on the patient's extremity with the slit opening around the surgical site and the adhesive strips holding the drape in a precise position around the surgical site.
Thus, it is seen that while there is an advantage in using fluid impervious layers in surgical extremity drapes, there has also generally been found a disadvantage in not having a close conforming fit of the drape to the surgical site.